import java.util.Scanner;

public class Text19092504 {
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		int x,y;
		x=scanner.nextInt();
		y=scanner.nextInt();
		if(x>=-1 && x<=1 && y>=-1 && y<=1) {
				System.out.println("yes");
			
		}else {
			System.out.println("no");
		}
		scanner.close();
	}
}
